A deer’s nose knows
DEER are members of the family biologists call Cervidae. Worldwide there are about 40 species of antlered animals. And to add to the complexity of it all, there are maybe four times that number of subspecies. In North America, we have five cervids, namely whitetail deer, mule deer , moose, elk and caribou. This makes our identification and study of these critters a little less daunting.
What sets all of the deer species apart is that the male Cervidae grow and discard antlers every year. No other animals do this. There is a bit of a twist to this rule of males only growing antlers with caribou. Female caribou do grow small antlers while bull caribou can and do grow impressive long beamed and multi-pointed head gear. Antlers are pure bone, the fastest growing bone known to science.
Horns are different than antlers. Horns are not shed annually but rather continue to add keratin material at its base all year long. In the category of horned North American wildlife are Bison, Muskox, Pronghorn Antelope, Bighorn Sheep, Dall’s Sheep, Desert Bighorn Sheep and Stone’s Sheep. Even in this group, a biologically unique critter is the Pronghorn. Its horn sheaths overlay and grow over a permanent boney skull extension. The sheaths are cast off each year. Four months later the horn sheath is replaced. But is is not an antler. Pronghorns are an exclusive unique animal to North American prairie grasslands.
Today’s image of the whitetail fawn appears to be a young male. The early stages of its antler buds, called pedicels, are faintly discernable above its eye. Later this year, those first year antlers will be at best little one inch long rounded knobs. If this fawn survives a normal life expectancy of maybe ten years, and all other factors being equal, it will grow larger antler sets each year for the first six years or so and then show a decline in antler structure. A deer living to age ten is possible, but most do not for a wide variety of factors outside of well regulated legal hunting seasons.
Fawns at this time of year are vulnerable to many issues they cope with. At the beginning, about eight weeks ago, this fawn kept a low profile of resting and hiding for most of the day. At birth it weighed about seven pounds after its seven-month long gestation. Like many four-legged animals, once it is born, the mother licks it clean and each learn of the unique scents of each other. The fawn is also imprinting on its mother, and will soon stand and be able to follow her wherever she goes. But a fawn is still weak and hungry. It will find its legs and learn to stand. Standing leads to walking, and walking leads to a food source, the mother’s udder and colostrum rich milk. Once fed, it will lay down in heavy cover while the doe deer separates herself from her fawn on purpose to keep distance as an protective measure should a predator pass nearby. The first two weeks of a fawn’s life is spend hiding. The doe returns to her fawn several times per day or at night to allow it to nurse.
Doe deer can also track their fawns by smelling the faint scents of the interdigital gland. This gland is located between the toes of its hoof on each of its four feet. Each step leaves a tell-tale trace of odor for the doe deer to follow. The gland secretions have been tested by biologists who named this yellowish waxy substance sebum. It contains 46 scent-emitting chemicals and each has a different rate of evaporation. A deer can smell these trace elements and know if the track is very fresh, somewhat old or very old. And it can help a deer know the direction of travel of the animal it seeks.
Deer also have additional scent glands that tell other deer all kinds of information about other deer in the territory. Glands on the head include nasal, forehead and preorbital. The forehead glands are use by bucks to rub against trees, branches or other vegetative items. It leaves a calling card of information as a sign post to every deer that passes by. Fifty-seven compounds have been identified from the forehead.
Not much is known about the function or purpose of the preorbital gland. However, tarsal glands on the inside of the back leg are much more familiar to people. A larger mat of hair captures extruded gland secretions and when mixed with the animal’s urine, leaves a host of chemical messages. For any deer, this calling card of information is a who’s who of what is happening on the landscape. Biologists have noted 63 compounds in female urine and 55 in male urine. Breeding adult buck deer have nine unique compounds while subordinate bucks have nineteen. So the deer’s nose knows what is going on its whitetail world.
The doe also can use subtle soft sounds to call to her fawn and bring it out of hiding. The spotted coat color helps provide camouflage to mimic sunlight that filters through forest tree leaves. Deer also make other grunt like calls for location or intimidation of others. Deer have excellent hearing, very good eyesight, especially at night, and a nose that can interpret all kinds of odors. The world of the white-tailed deer is an interesting part of natural history and biology.
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WILDLIFE ROADSIDE COUNTS will begin Monday all across Iowa. More than 200 standardized 30 mile long routes will be driven by biologists and game wardens. Careful note will be made of what is observed with particular emphasis on pheasants, both roosters or hens with chicks, gray partridge, rabbits and a sprinkling of other species. This is an early morning survey preferably conducted with calm to light winds, heavy dew from the night before, and clear to party cloudy skies. Heavy dew makes the critter’s coats or feathers wet and in attempts to dry off, may seek out gravel roadways to let warm sunlight assist in evaporating the moisture. That is why the counting is possible as observers slowly traverse these designated routes.
All the survey routes will be completed during the next two weeks. And when the data is gathered and fed into trend line data computer programs, biologists can decipher population ups and downs for various upland game species. That is how it works. It is always interesting to compare data from past years, and factor in weather events that helped or hindered wildlife reproduction. What can be said even at this point is that pheasant numbers are higher than last year. Only the survey data can attempt to quantify how much. So stay tuned and we will learn together by the end of August what Iowa’s roadside wildlife survey route can tell us.
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Citizen science can help with data collection for WILD TURKEYS. The time is now to carefully watch for and see wild turkey hens and her young poults. Note the date, time and general location of any hen turkeys and how many young she has following. Note the size of the young turkeys. Then call Peter Fritzell at the Iowa DNR wildlife bureau at 515-432-2823 to report your sighting. It is that easy.
Hunters this past spring in Iowa hunted for wild turkeys. At the end of the season on May 22, approximately 12,200 tom tom turkeys (or beaded turkeys) were harvested. Licenses sold for this privilege were over 51,000. Marshall County turkey hunters took about 70. Nationally wild turkeys in 1900 were down to an estimated 100,000 birds due to habitat loss and unregulated takings. Today, thanks to legal well-regulated seasons, habitat improvements and cooperative programs between states and private conservation organizations like the Wild Turkey Federation, the population of turkeys is now at 7 million!
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Hunting is Conservation. How? The hunting sports provide the backbone of all financial support for huntable species and a huge portion of all habitat conservation pursuits that benefit every non-game animal you can name. Funds come from license sales, special stamp or fee requirements, and an eleven percent tax on hunting guns, ammo, archery sales. Just the federal excise taxes alone bring in $371 million dollars per year. This money is proportioned back to the states in proportion to licenses sales and a host of other factors. Annual contributions from hunters for conservation tallies an amazing $1.6 billion!
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“If we do not plant knowledge when young, it will give no shade when we are old.”
– Lord Chesterfield, statesman
Garry Brandenburg is a graduate of Iowa State University with BS degree in Fish & Wildlife Biology. He is the retired director of the Marshall County Conservation Board. Contact him at P.O. Box 96, Albion, IA 50005.